Abstract: Application of urease inhibitor/nitrification inhibitor can effectively control soil nitrogen (N) transformation, reduce N loss, and improve N use efficiency of crops. In this study, an experiment was conducted to investigate the effects of biochemical inhibitors (NBPT/NPPT+CP) combined with fertilization mode (once or three times) and their interactions on rice yield, yield components, and economic benefit in yellow clayey field using two factor randomized block design. The results showed that biochemical inhibitor combination and fertilization mode had significant effects on rice yield and economic benefit (P<0.001), whereas their interaction effect was not significant (P>0.05). Three time urea fertilization treatment (U3) significantly increased grain yield and economic benefit by 14.2% and 14.6% (P<0.05), respectively, compared to once fertilization treatment (U). Compared with U treatment, U+NBPT, U+NPPT, U+CP, U+NBPT+CP, U+NPPT+CP treatments significantly increased rice yield by 22.8%, 22.2%, 20.1%, 24.1% and 25.8% (P<0.05), and economic benefit by 25.2%, 24.6%, 22.2%, 26.2% and 28.1% (P<0.05), respectively. Compared with U3 treatment, U3+NBPT, U3+NPPT, U3+CP, U3+NBPT+CP, U3+NPPT+CP treatments significantly increased rice yield by 10.8%, 13.5%, 12.8%, 12.0% and 15.8% (P<0.05), and economic benefit by 11.7%, 14.7%, 14.0%, 12.6% and 16.8% (P<0.05), respectively. Addition of a newtype urease inhibitor NPPT alone or combined with CP had a yieldincreasing effect similar to that of NBPT. Path analysis showed that the direct effect of once fertilization on rice yield ranked as 1000-grain weight (0.460)>effective panicles (0.436) >grains per panicle (0.385); three-time fertilization ranked as effective panicles (1.040)>grains per panicle (0.304)>1000 grain weight (-0.059). In conclusion, fertilization plus inhibitor application can effectively enhance the grain sink and increase rice production with better income in yellow clayey field, and can further improve the production potential of crop varieties when combined with a suitable fertilization mode.

Key words: emission list, fluorine, soil., electrolytic aluminum